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    <span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></nav>  <ul class="sidebar-links"><li><a href="/vue3/api/application-config.html" class="sidebar-link">应用配置</a></li><li><a href="/vue3/api/application-api.html" class="sidebar-link">应用 API</a></li><li><a href="/vue3/api/global-api.html" class="sidebar-link">全局 API</a></li><li><section class="sidebar-group depth-0"><a href="/vue3/api/options-api" class="sidebar-heading clickable"><span>选项</span> <!----></a> <ul class="sidebar-links sidebar-group-items"><li><a href="/vue3/api/options-data.html" class="sidebar-link">Data</a></li><li><a href="/vue3/api/options-dom.html" class="sidebar-link">DOM</a></li><li><a href="/vue3/api/options-lifecycle-hooks.html" class="sidebar-link">生命周期钩子</a></li><li><a href="/vue3/api/options-assets.html" class="sidebar-link">选项/资源</a></li><li><a href="/vue3/api/options-composition.html" class="sidebar-link">组合</a></li><li><a href="/vue3/api/options-misc.html" class="sidebar-link">杂项</a></li></ul></section></li><li><a href="/vue3/api/instance-properties.html" class="sidebar-link">实例 property</a></li><li><a href="/vue3/api/instance-methods.html" class="sidebar-link">实例方法</a></li><li><a href="/vue3/api/directives.html" class="sidebar-link">指令</a></li><li><a href="/vue3/api/special-attributes.html" class="sidebar-link">特殊 attribute</a></li><li><a href="/vue3/api/built-in-components.html" class="sidebar-link">内置组件</a></li><li><section class="sidebar-group depth-0"><a href="/vue3/api/reactivity-api" class="sidebar-heading clickable open"><span>响应性 API</span> <!----></a> <ul class="sidebar-links sidebar-group-items"><li><a href="/vue3/api/basic-reactivity.html" aria-current="page" class="active sidebar-link">响应性基础 API</a><ul class="sidebar-sub-headers"><li class="sidebar-sub-header"><a href="/vue3/api/basic-reactivity.html#reactive" class="sidebar-link">reactive</a></li><li class="sidebar-sub-header"><a href="/vue3/api/basic-reactivity.html#readonly" class="sidebar-link">readonly</a></li><li class="sidebar-sub-header"><a href="/vue3/api/basic-reactivity.html#isproxy" class="sidebar-link">isProxy</a></li><li class="sidebar-sub-header"><a href="/vue3/api/basic-reactivity.html#isreactive" class="sidebar-link">isReactive</a></li><li class="sidebar-sub-header"><a href="/vue3/api/basic-reactivity.html#isreadonly" class="sidebar-link">isReadonly</a></li><li class="sidebar-sub-header"><a href="/vue3/api/basic-reactivity.html#toraw" class="sidebar-link">toRaw</a></li><li class="sidebar-sub-header"><a href="/vue3/api/basic-reactivity.html#markraw" class="sidebar-link">markRaw</a></li><li class="sidebar-sub-header"><a href="/vue3/api/basic-reactivity.html#shallowreactive" class="sidebar-link">shallowReactive</a></li><li class="sidebar-sub-header"><a href="/vue3/api/basic-reactivity.html#shallowreadonly" class="sidebar-link">shallowReadonly</a></li></ul></li><li><a href="/vue3/api/refs-api.html" class="sidebar-link">Refs</a></li><li><a href="/vue3/api/computed-watch-api.html" class="sidebar-link">Computed 与 watch</a></li><li><a href="/vue3/api/effect-scope.html" class="sidebar-link">Effect 作用域 API</a></li></ul></section></li><li><a href="/vue3/api/composition-api.html" class="sidebar-link">组合式 API</a></li><li><section class="sidebar-group depth-0"><p class="sidebar-heading"><span>单文件组件</span> <!----></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/vue3/api/sfc-spec.html" class="sidebar-link">规范</a></li><li><a href="/vue3/api/sfc-tooling.html" class="sidebar-link">工具</a></li><li><a href="/vue3/api/sfc-script-setup.html" class="sidebar-link">&lt;script setup&gt;</a></li><li><a href="/vue3/api/sfc-style.html" class="sidebar-link">&lt;style&gt; 特性</a></li></ul></section></li></ul> </aside> <main class="page"><div class="carbon-ads"></div>  <div class="theme-default-content content__default"><h1 id="响应性基础-api"><a href="#响应性基础-api" class="header-anchor">#</a> 响应性基础 API</h1> <blockquote><p>本节例子中代码使用<a href="/vue3/guide/single-file-component.html">单文件组件</a>语法</p></blockquote> <h2 id="reactive"><a href="#reactive" class="header-anchor">#</a> <code>reactive</code></h2> <p>返回对象的响应式副本</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">const</span> obj <span class="token operator">=</span> <span class="token function">reactive</span><span class="token punctuation">(</span><span class="token punctuation">{</span> count<span class="token operator">:</span> <span class="token number">0</span> <span class="token punctuation">}</span><span class="token punctuation">)</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>响应式转换是“深层”的——它影响所有嵌套 property。在基于 <a href="https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/Proxy" target="_blank" rel="noopener noreferrer">ES2015 Proxy<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a> 的实现中，返回的 proxy 是<strong>不</strong>等于原始对象的。建议只使用响应式 proxy，避免依赖原始对象。</p> <p><strong>类型声明：</strong></p> <div class="language-ts line-numbers-mode"><pre class="language-ts"><code><span class="token keyword">function</span> <span class="token generic-function"><span class="token function">reactive</span><span class="token generic class-name"><span class="token operator">&lt;</span><span class="token constant">T</span> <span class="token keyword">extends</span> object<span class="token operator">&gt;</span></span></span><span class="token punctuation">(</span>target<span class="token operator">:</span> <span class="token constant">T</span><span class="token punctuation">)</span><span class="token operator">:</span> UnwrapNestedRefs<span class="token operator">&lt;</span><span class="token constant">T</span><span class="token operator">&gt;</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><div class="custom-block tip"><p class="custom-block-title">提示</p> <p><code>reactive</code> 将解包所有深层的 <a href="/vue3/api/refs-api.html#ref">refs</a>，同时维持 ref 的响应性。</p> <div class="language-ts line-numbers-mode"><pre class="language-ts"><code><span class="token keyword">const</span> count <span class="token operator">=</span> <span class="token function">ref</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>
<span class="token keyword">const</span> obj <span class="token operator">=</span> <span class="token function">reactive</span><span class="token punctuation">(</span><span class="token punctuation">{</span> count <span class="token punctuation">}</span><span class="token punctuation">)</span>

<span class="token comment">// ref 会被解包</span>
<span class="token builtin">console</span><span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>obj<span class="token punctuation">.</span>count <span class="token operator">===</span> count<span class="token punctuation">.</span>value<span class="token punctuation">)</span> <span class="token comment">// true</span>

<span class="token comment">// 它会更新 `obj.count`</span>
count<span class="token punctuation">.</span>value<span class="token operator">++</span>
<span class="token builtin">console</span><span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>count<span class="token punctuation">.</span>value<span class="token punctuation">)</span> <span class="token comment">// 2</span>
<span class="token builtin">console</span><span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>obj<span class="token punctuation">.</span>count<span class="token punctuation">)</span> <span class="token comment">// 2</span>

<span class="token comment">// 它也会更新 `count` ref</span>
obj<span class="token punctuation">.</span>count<span class="token operator">++</span>
<span class="token builtin">console</span><span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>obj<span class="token punctuation">.</span>count<span class="token punctuation">)</span> <span class="token comment">// 3</span>
<span class="token builtin">console</span><span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>count<span class="token punctuation">.</span>value<span class="token punctuation">)</span> <span class="token comment">// 3</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br></div></div></div> <div class="custom-block warning"><p class="custom-block-title">重要</p> <p>当将 <a href="/vue3/api/refs-api.html#ref">ref</a> 分配给 <code>reactive</code> property 时，ref 将被自动解包。</p> <div class="language-ts line-numbers-mode"><pre class="language-ts"><code><span class="token keyword">const</span> count <span class="token operator">=</span> <span class="token function">ref</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>
<span class="token keyword">const</span> obj <span class="token operator">=</span> <span class="token function">reactive</span><span class="token punctuation">(</span><span class="token punctuation">{</span><span class="token punctuation">}</span><span class="token punctuation">)</span>

obj<span class="token punctuation">.</span>count <span class="token operator">=</span> count

<span class="token builtin">console</span><span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>obj<span class="token punctuation">.</span>count<span class="token punctuation">)</span> <span class="token comment">// 1</span>
<span class="token builtin">console</span><span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>obj<span class="token punctuation">.</span>count <span class="token operator">===</span> count<span class="token punctuation">.</span>value<span class="token punctuation">)</span> <span class="token comment">// true</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br></div></div></div> <h2 id="readonly"><a href="#readonly" class="header-anchor">#</a> <code>readonly</code></h2> <p>接受一个对象 (响应式或纯对象) 或 <a href="/vue3/api/refs-api.html#ref">ref</a> 并返回原始对象的只读代理。只读代理是深层的：任何被访问的嵌套 property 也是只读的。</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">const</span> original <span class="token operator">=</span> <span class="token function">reactive</span><span class="token punctuation">(</span><span class="token punctuation">{</span> count<span class="token operator">:</span> <span class="token number">0</span> <span class="token punctuation">}</span><span class="token punctuation">)</span>

<span class="token keyword">const</span> copy <span class="token operator">=</span> <span class="token function">readonly</span><span class="token punctuation">(</span>original<span class="token punctuation">)</span>

<span class="token function">watchEffect</span><span class="token punctuation">(</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
  <span class="token comment">// 用于响应性追踪</span>
  console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>copy<span class="token punctuation">.</span>count<span class="token punctuation">)</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span>

<span class="token comment">// 变更 original 会触发依赖于副本的侦听器</span>
original<span class="token punctuation">.</span>count<span class="token operator">++</span>

<span class="token comment">// 变更副本将失败并导致警告</span>
copy<span class="token punctuation">.</span>count<span class="token operator">++</span> <span class="token comment">// 警告!</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br></div></div><p>与 <a href="#reactive"><code>reactive</code></a> 一样，如果任何 property 使用了 <code>ref</code>，当它通过代理访问时，则被自动解包：</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">const</span> raw <span class="token operator">=</span> <span class="token punctuation">{</span>
  count<span class="token operator">:</span> <span class="token function">ref</span><span class="token punctuation">(</span><span class="token number">123</span><span class="token punctuation">)</span>
<span class="token punctuation">}</span>

<span class="token keyword">const</span> copy <span class="token operator">=</span> <span class="token function">readonly</span><span class="token punctuation">(</span>raw<span class="token punctuation">)</span>

console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>raw<span class="token punctuation">.</span>count<span class="token punctuation">.</span>value<span class="token punctuation">)</span> <span class="token comment">// 123</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>copy<span class="token punctuation">.</span>count<span class="token punctuation">)</span> <span class="token comment">// 123</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br></div></div><h2 id="isproxy"><a href="#isproxy" class="header-anchor">#</a> <code>isProxy</code></h2> <p>检查对象是否是由 <a href="#reactive"><code>reactive</code></a> 或 <a href="#readonly"><code>readonly</code></a> 创建的 proxy。</p> <h2 id="isreactive"><a href="#isreactive" class="header-anchor">#</a> <code>isReactive</code></h2> <p>检查对象是否是由 <a href="#reactive"><code>reactive</code></a> 创建的响应式代理。</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">import</span> <span class="token punctuation">{</span> reactive<span class="token punctuation">,</span> isReactive <span class="token punctuation">}</span> <span class="token keyword">from</span> <span class="token string">'vue'</span>
<span class="token keyword">export</span> <span class="token keyword">default</span> <span class="token punctuation">{</span>
  <span class="token function">setup</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">const</span> state <span class="token operator">=</span> <span class="token function">reactive</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
      name<span class="token operator">:</span> <span class="token string">'John'</span>
    <span class="token punctuation">}</span><span class="token punctuation">)</span>
    console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token function">isReactive</span><span class="token punctuation">(</span>state<span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token comment">// -&gt; true</span>
  <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br></div></div><p>如果该代理是 <a href="#readonly"><code>readonly</code></a> 创建的，但包裹了由 <a href="#reactive"><code>reactive</code></a> 创建的另一个代理，它也会返回 <code>true</code>。</p> <div class="language-js line-numbers-mode"><div class="highlight-lines"><br><br><br><br><br><br><div class="highlighted"> </div><div class="highlighted"> </div><div class="highlighted"> </div><div class="highlighted"> </div><div class="highlighted"> </div><div class="highlighted"> </div><div class="highlighted"> </div><div class="highlighted"> </div><div class="highlighted"> </div><br><br><br></div><pre class="language-js"><code><span class="token keyword">import</span> <span class="token punctuation">{</span> reactive<span class="token punctuation">,</span> isReactive<span class="token punctuation">,</span> readonly <span class="token punctuation">}</span> <span class="token keyword">from</span> <span class="token string">'vue'</span>
<span class="token keyword">export</span> <span class="token keyword">default</span> <span class="token punctuation">{</span>
  <span class="token function">setup</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">const</span> state <span class="token operator">=</span> <span class="token function">reactive</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
      name<span class="token operator">:</span> <span class="token string">'John'</span>
    <span class="token punctuation">}</span><span class="token punctuation">)</span>
    <span class="token comment">// 从普通对象创建的只读 proxy</span>
    <span class="token keyword">const</span> plain <span class="token operator">=</span> <span class="token function">readonly</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
      name<span class="token operator">:</span> <span class="token string">'Mary'</span>
    <span class="token punctuation">}</span><span class="token punctuation">)</span>
    console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token function">isReactive</span><span class="token punctuation">(</span>plain<span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token comment">// -&gt; false</span>

    <span class="token comment">// 从响应式 proxy 创建的只读 proxy</span>
    <span class="token keyword">const</span> stateCopy <span class="token operator">=</span> <span class="token function">readonly</span><span class="token punctuation">(</span>state<span class="token punctuation">)</span>
    console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token function">isReactive</span><span class="token punctuation">(</span>stateCopy<span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token comment">// -&gt; true</span>
  <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
</code></pre><div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br></div></div><h2 id="isreadonly"><a href="#isreadonly" class="header-anchor">#</a> <code>isReadonly</code></h2> <p>检查对象是否是由 <a href="#readonly"><code>readonly</code></a> 创建的只读代理。</p> <h2 id="toraw"><a href="#toraw" class="header-anchor">#</a> <code>toRaw</code></h2> <p>返回 <a href="#reactive"><code>reactive</code></a> 或 <a href="#readonly"><code>readonly</code></a> 代理的原始对象。这是一个“逃生舱”，可用于临时读取数据而无需承担代理访问/跟踪的开销，也可用于写入数据而避免触发更改。<strong>不</strong>建议保留对原始对象的持久引用。请谨慎使用。</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">const</span> foo <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token punctuation">}</span>
<span class="token keyword">const</span> reactiveFoo <span class="token operator">=</span> <span class="token function">reactive</span><span class="token punctuation">(</span>foo<span class="token punctuation">)</span>

console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token function">toRaw</span><span class="token punctuation">(</span>reactiveFoo<span class="token punctuation">)</span> <span class="token operator">===</span> foo<span class="token punctuation">)</span> <span class="token comment">// true</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br></div></div><h2 id="markraw"><a href="#markraw" class="header-anchor">#</a> <code>markRaw</code></h2> <p>标记一个对象，使其永远不会转换为 proxy。返回对象本身。</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">const</span> foo <span class="token operator">=</span> <span class="token function">markRaw</span><span class="token punctuation">(</span><span class="token punctuation">{</span><span class="token punctuation">}</span><span class="token punctuation">)</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token function">isReactive</span><span class="token punctuation">(</span><span class="token function">reactive</span><span class="token punctuation">(</span>foo<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token comment">// false</span>

<span class="token comment">// 嵌套在其他响应式对象中时也可以使用</span>
<span class="token keyword">const</span> bar <span class="token operator">=</span> <span class="token function">reactive</span><span class="token punctuation">(</span><span class="token punctuation">{</span> foo <span class="token punctuation">}</span><span class="token punctuation">)</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token function">isReactive</span><span class="token punctuation">(</span>bar<span class="token punctuation">.</span>foo<span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token comment">// false</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br></div></div><div class="custom-block warning"><p class="custom-block-title">重要</p> <p><code>markRaw</code> 和下方的 shallowXXX API 使你可以有选择地退出默认的深度响应式/只读转换模式，并将原始的，未被代理的对象嵌入状态图中。它们可以根据情况灵活运用：</p> <ul><li>有些值不应该是响应式的，例如复杂的第三方类实例或 Vue 组件对象。</li> <li>当渲染具有不可变数据源的大列表时，跳过 proxy 转换可以提高性能。</li></ul> <p>这些例子是进阶的运用，因为原始选择退出仅在根级别，因此，如果将嵌套在内的、未标记的原始对象添加进响应式对象，然后再次访问该响应式对象，就会得到原始对象被代理后的版本。这可能会导致<strong>同一性风险</strong>——即执行一个依赖于对象本身的操作，但同时使用同一对象的原始版本和被代理后的版本：</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">const</span> foo <span class="token operator">=</span> <span class="token function">markRaw</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
  nested<span class="token operator">:</span> <span class="token punctuation">{</span><span class="token punctuation">}</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span>

<span class="token keyword">const</span> bar <span class="token operator">=</span> <span class="token function">reactive</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
  <span class="token comment">// 虽然 `foo` 被标记为原始，但 foo.nested 不是。</span>
  nested<span class="token operator">:</span> foo<span class="token punctuation">.</span>nested
<span class="token punctuation">}</span><span class="token punctuation">)</span>

console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>foo<span class="token punctuation">.</span>nested <span class="token operator">===</span> bar<span class="token punctuation">.</span>nested<span class="token punctuation">)</span> <span class="token comment">// false</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br></div></div><p>同一性风险通常很少见。然而，为了正确地使用这些 API，同时安全地避免同一性风险，就需要对响应性系统的工作原理有一个充分的理解。</p></div> <h2 id="shallowreactive"><a href="#shallowreactive" class="header-anchor">#</a> <code>shallowReactive</code></h2> <p>创建一个响应式代理，它跟踪其自身 property 的响应性，但不执行嵌套对象的深层响应式转换 (暴露原始值)。</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">const</span> state <span class="token operator">=</span> <span class="token function">shallowReactive</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
  foo<span class="token operator">:</span> <span class="token number">1</span><span class="token punctuation">,</span>
  nested<span class="token operator">:</span> <span class="token punctuation">{</span>
    bar<span class="token operator">:</span> <span class="token number">2</span>
  <span class="token punctuation">}</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span>

<span class="token comment">// 改变 state 本身的性质是响应式的</span>
state<span class="token punctuation">.</span>foo<span class="token operator">++</span>
<span class="token comment">// ...但是不转换嵌套对象</span>
<span class="token function">isReactive</span><span class="token punctuation">(</span>state<span class="token punctuation">.</span>nested<span class="token punctuation">)</span> <span class="token comment">// false</span>
state<span class="token punctuation">.</span>nested<span class="token punctuation">.</span>bar<span class="token operator">++</span> <span class="token comment">// 非响应式</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br></div></div><p>与 <a href="#reactive"><code>reactive</code></a> 不同，任何使用 <a href="/vue3/api/refs-api.html#ref"><code>ref</code></a> 的 property 都<strong>不会</strong>被代理自动解包。</p> <h2 id="shallowreadonly"><a href="#shallowreadonly" class="header-anchor">#</a> <code>shallowReadonly</code></h2> <p>创建一个 proxy，使其自身的 property 为只读，但不执行嵌套对象的深度只读转换 (暴露原始值)。</p> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">const</span> state <span class="token operator">=</span> <span class="token function">shallowReadonly</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
  foo<span class="token operator">:</span> <span class="token number">1</span><span class="token punctuation">,</span>
  nested<span class="token operator">:</span> <span class="token punctuation">{</span>
    bar<span class="token operator">:</span> <span class="token number">2</span>
  <span class="token punctuation">}</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span>

<span class="token comment">// 改变 state 本身的 property 将失败</span>
state<span class="token punctuation">.</span>foo<span class="token operator">++</span>
<span class="token comment">// ...但适用于嵌套对象</span>
<span class="token function">isReadonly</span><span class="token punctuation">(</span>state<span class="token punctuation">.</span>nested<span class="token punctuation">)</span> <span class="token comment">// false</span>
state<span class="token punctuation">.</span>nested<span class="token punctuation">.</span>bar<span class="token operator">++</span> <span class="token comment">// 适用</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br></div></div><p>与 <a href="#readonly"><code>readonly</code></a> 不同，任何使用 <a href="/vue3/api/refs-api.html#ref"><code>ref</code></a> 的 property 都<strong>不会</strong>被代理自动解包。</p></div> <footer class="page-edit" data-v-007274aa><div class="container" data-v-007274aa><p data-v-007274aa><span class="edit-link" data-v-007274aa>
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